This invention relates to improvements in and concerning a method for fixing microorganisms. More particularly, the present invention relates to a microorganism method of reaction for the decomposition or synthesis of a reaction substrate, which method is characterized by utilizing conditions for permitting a microorganism to be positively retained and grown on a support in the cultivation of the microorganism and by causing the reaction substrate to come into contact with the support on which the microorganism has been retained.
In recent years, microorganisms have been finding extensive utility in disposal of effluents responsible for environmental pollution, production of foodstuffs, manufacture of pharmaceutical goods, etc.
In one area of the utility, microorganisms are used for producing enzymes, which are adopted to effect various biochemical reactions leading to production of useful substances. Such enzymatic reactions were formerly carried out by a batchwise method wherein either the enzymes themselves or microorganism cells containing such enzymes were incorporated in reaction substrates. Ther have since been developed methods for fixing enzymes in proper carriers or for fixing enzymes in the microorganism cells in which they are produced (for example, these methods disclosed in U.S. Pat. Nos. 3,752,858, 3,933,587 and 3,950,222), making it feasible for desired enzymatic reactions to be continuously carried out. These methods have invariably had a fatal disadvantage in that the microorganism cells which have produced the enzymes are no longer allowed to propagate because the cells are dead at the time the enzymes are fixed therein or because the enzymes are extracted from the cells prior to the fixation in the carriers and that, consequently, the activities of the fixed enzymes inevitably gradually decrease with the progress of the enzymatic reactions involved.
The inventors have suggested a method for the decomposition of phthalic acid esters by use of a microorganism (U.S. Pat. No. 4,133,752). This method comprises incorporating a phthalic acid ester in a culture medium and culturing a specific microorganism in said medium for thereby causing the microorganism to propagate and assimilate the phthalic acid ester to effect the required decomposition. By this method, however, it has been difficult to effect the decomposition of the phthalic acid ester in a continuous process.
Besides, U.S. Pat. No. 2,793,096 discloses a method for de-odorizing an odorous gas by forcing the gas to flow into a gas-permeable soil bed inhabited by a microorganism and thereby causing the odors present in the gas to be oxidized by the microorganism. This method, however, makes use of the microorganism existing from the beginning in the soil bed and the substance to be treated thereby is a gaseous matter. That is to say, the reaction efficiency of this method depends completely upon a microorganism which might by chance exist in the soil bed. When the soil bed to be used contains therein no microorganism capable of oxidizing and de-odorizing odorous substances, it is self-evident that good results cannot be expected by this method.
An object of the present invention is to provide a microorganism method for enabling a biochemical treatment for decomposition or synthesis to be performed continuously and effectively by the agency of a microorganism for a long period of time.